This year is heading to be the hottest or second hottest on record, according to the Met Office. It says the past 12 months are the warmest recorded by Nasa, and are second in the UK data set, HadCRUT3.

The Met Office says it is very confident that man-made global warming is forcing up temperatures.Until now, the hottest year on record has been 1998, when temperatures were pushed up by a strong El Nino - a warming event in the Pacific.

With the number of salmon in the North Pacific having doubled in the past 50 years, scientists are increasingly concerned there may not be enough food to support them, and changing ocean conditions could make it even worse.

On the surface, the mounting scientific evidence would seem to contradict conventional wisdom that salmon are a disappearing species. But as with everything salmon, it's more complicated.

The Obama administration is setting aside 187,000 square miles in Alaska as a "critical habitat" for polar bears, an action that could restrict future offshore drilling for oil and gas. The total, which includes large areas of sea ice off the Alaska coast, is about 13,000 square miles, or 8.3 million acres, less than in a preliminary plan released last year.

Tom Strickland, assistant secretary for fish, wildlife and parks at the Interior Department, said the designation would help polar bears stave off extinction, recognizing that the greatest threat is the melting of Arctic sea ice caused by climate change.

The oil is still there, sitting at the bottom of the Gulf of Mexico and causing damage to the environment, a Florida State University professor who studies greenhouse gases, oceans and energy said Tuesday.

Professor Jeff Chanton compared natural oil seepage in the Gulf of Mexico to the Deepwater Horizon oil spill. About 1,000 natural ocean-floor leaks combine to trickle about 400,000 barrels of oil into the Gulf each year, Chanton said, but scientists estimate as many as 60,000 barrels of oil poured into the Gulf each day of the spill.

Russian Prime Minister Vladimir Putin and Chinese Premier Wen Jiabao on Tuesday agreed with other Asian nations to try to double the world's wild tiger population by 2022 and save it from extinction.

Just 3,200 tigers now live in the wild, down from 100,000 a century ago, and those that remain face a losing battle with poachers who supply traders in India and China with tiger parts for traditional medicines and purported aphrodisiacs.

Experts in the safety of genetically modified (GM) organisms have expressed concern over the release of GM mosquitoes into the wild on the Cayman Islands, which was publicised internationally only last month — a year after their initial release.

The trial of the OX513A strain of the dengue-carrying Aedes aegypti mosquito, developed by UK biotechnology company Oxitec, was carried out on Grand Cayman island by the Cayman Islands' Mosquito Research and Control Unit (MRCU) in 2009, followed by a bigger release between May and October this year. Together they represent the first known release of GM mosquitoes anywhere in the world.